Earlier this year, Guo Wengui, an expatriate Chinese billionaire, began to make explosive allegations on YouTube and Twitter about China’s leaders. President Xi Jinping, Guo claimed, had sought incriminating information about Wang Qishan, Xi’s right-hand man and the chief of his anticorruption campaign. The figure tasked with rooting out China’s official graft, Guo suggested, was himself corrupt—if not directly, then through his family’s alleged financial holdings.

Guo’s claims seemed designed to sever China’s most important political relationship before this fall’s 19th Party Congress, where officials will determine Xi’s longevity as president and select members for China’s top decision-making bodies. Xi’s power rests in part on Wang’s anticorruption campaign, and any deterioration in the relationship between the two men–real or perceived–could embolden Xi’s rivals or rattle his supporters, who may defect to his opponents.

Guo has neither named a source nor provided conclusive evidence for his claims, and their validity is unclear. Nevertheless, the allegations have signaled the emergence of a new tool in Chinese politics: weaponized leaks. As the infighting within the Chinese Communist Party has intensified, Guo has shown, elites can undermine their rivals by implicating them in the widespread collusion between China’s political and economic leaders.

Xi himself has sought to oust his challengers by ensnaring them in corruption scandals. But Guo’s actions show that by placing allegations in the media outside of China, those without direct access to the levers of power can now do the same, betting that their claims abroad will leap over the so-called Great Firewall, reenter China, and reshape the country’s domestic politics.

All of this raises questions about China’s political stability. What will stop other insiders from making similarly explosive disclosures about party politics? At stake is not only the outcome of the coming Party Congress, but the future of China’s opaque political system.